1. Field of the Invention
The present invention relates to a fluid reservoir for master cylinder and more particularly to a fluid reservoir which characterizes a reservoir cap holding mechanism.
2. Description of the Prior Art
Conventionally, many mechanisms have been used as reservoir cap holding mechanism. In a first typical conventional mechanism, a reservoir cap is held on a reservoir by engagement between an elastically deformable annular fringe portion thereof and an outer periphery of an upper end portion, provided with an outward flange, of the reservoir. In a second conventional mechanism, a reservoir cap is held on a reservoir by engagement between an elastically deformable central boss portion thereof and an inner periphery of an upper end portion of the reservoir.
In a third conventional mechanism, a reservoir cap is held on a reservoir by screw-engagement between the reservoir cap and an upper end portion of the reservoir. In a fourth conventional mechanism, a reservoir cap is held on a reservoir by engagement between a nail member thereof and a member, corresponding to the nail, on the reservoir. The engagement between the nail member of the reservoir cap and the member on the reservoir is released by turning the reservoir cap.
However, in the first and second conventional mechanisms, great effort is required to attach or detach the reservoir cap to or from the reservoir, since the fringe portion or the boss portion of the reservoir cap is provided with relatively greater elasticity for sealingly closing an upper opening of the reservoir. Furthermore, in the first conventional mechanism, it is difficult to measure the misalignment between the reservoir cap and the reservoir thereby causing fluid leakage out of the reservoir. In the third conventional mechanism, a relatively longer time is required to attach or detach the reservoir cap to or from the reservoir. Moreover, in the fourth conventional mechanism, a sealing member, which is provided on the reservoir cap and is in sealing engagement with an inner peripheral wall of the reservoir when the reservoir cap is attached to the reservoir, is twisted upon turning of the reservoir cap thereby causing damage to the sealing member.